Off-axis parabolic mirrors provide an unobstructed aperture allowing complete access to the focal region as well as reducing the size and minimising the weight of a design
Parabolic mirrors are the most common type of aspherical mirrors used in optical instruments.
They are free from spherical aberrations, and thus focus a parallel beam to a point or a point source to infinity.
Off-axis parabolic mirrors provide an unobstructed aperture allowing complete access to the focal region as well as reducing the size and minimising the weight of a design.
They are especially suitable for broadband or multiple wavelength applications due to their completely achromatic performance.
All together these advantages produce a cost-effective solution for many optical design problems with no compromise in performance.
Because of these notable advantages, Optical Surfaces reports that it regularly supplies high precision off-axis parabolic mirrors for high power laser focusing, focusing astronomical objects, and producing collimated reference wavefronts.
Other applications that have benefited from the company's high precision off-axis parabolic mirrors include beam expansion, MTF measurement, MRTD testing and bore sight alignment for missile guidance systems.
Typical specifications achieved include off-axis parabolic mirrors up to 600mm in diameter with surface accuracies to lambda/20p-v, depending upon off-axis angles.
With proprietary polishing techniques the company says it can, depending on the surface accuracy required, achieve the natural limit to the off-axis angle of around 25-30 degrees and surface micro-roughness on aspherics of ~1nmRMS.
A range of coatings is available for standard and custom components from metallic with or without protective overcoat to multilayer dielectrics and ultra hard coatings.
Production approved to ISO 9001-2000 means the quality of off-axis paraboloids from Optical Surfaces is ensured both by long experience and a range of interferometric and surface test measurements on all optics and optical systems leaving the factory, the company says.
